Jens Weidmann, head of the Bundesbank and the ECB’s dominant governor, said that any move to leverage Europe’s €440bn rescue fund through central bank financing would be a “clear violation” of the ECB’s legal mandate.

He said Article 123 of the EU Treaty imposed a legal “prohibition on monetary financing”, implying that the ECB cannot attempt to shore up the debt markets of Italy and Spain for covert fiscal support.

Mr Weidmann said Germany learned the bitter lesson under the Weimar Republic that funding public debt “via the money printing press” leads to hyperinflation and disaster.

The comments came a day after Britain’s Prime Minister said it was “difficult to understand” why the ECB was not “doing more” to halt contagion, a view shared in Washington, Beijing and Tokyo.

Asia’s creditor states are scornful of requests to help rescue Europe when the ECB itself refuses to take on the role of lender of last resort. However, there is some dispute over whether the ECB is technically able to take on that role even if it dares bend the law any further. “The ECB is not indemnified by a eurozone treasury, because there is no such treasury,” said Julian Callow from Barclays Capital.

The Bank of England and the US Federal Reserve have explicit guarantees from national treasuries that any losses stemming from bond purchases will be compensated, giving them the “credibility halo” of sovereign states.